The present invention relates to laminated glass having heat shielding properties (hereinafter referred to as IR cutoff properties).
Vehicles mount heat shielding windowpanes in order to intercept incident solar energy into the compartment and decrease the temperature rise in the compartment and the load on the air conditioner. As heat shielding windowpanes, thin film-deposited glass sheets having thin films of various metals and metal oxides layered on the glass surfaces may be mentioned. Because of the electrical conductivity of films of these various metals and metal oxides, thin film-deposited glass sheets intercept radio waves.
On the other hand, as windowpanes for vehicles, especially for automobiles, glass sheets having the functions of radio, TV and GPS antennas are often used. Automobiles equipped with various functional systems (such as the electric road pricing system and the keyless entry system) including sensors installed inside them to send out or receive radio waves are also proposed. In order to secure the normal function as an antenna and normal operations of various systems, windowpanes have to transmit radio waves.
Therefore, thin film-deposited glass sheets need special tuning to secure the function as an antenna. Further, thin film-deposited glass sheets can hardly be used directly for systems that require transmission of electric waves for radio communication between inside and outside vehicles.
From this viewpoint, a laminated glass that transmits radio waves as well as intercepts heat radiation is disclosed in JP-A-8-259279. The laminated glass disclosed therein uses an interlayer in which functional fine particles with particle diameters of at most 0.2 xcexcm are dispersed. The laminated glass is supposed to not only intercept heat radiation but also suppress radio interference.
However, this laminated glass has an unfavorable appearance due to the functional fine particles dispersed in the interlayer. In other words, incorporation of as many fine particles as necessary for satisfactory IR cutoff properties for windowpanes of automobiles results in an interlayer having a high haze and hence a laminated glass having a high haze.
The object of the present invention is to provide a laminated glass with a less unfavorable appearance and IR cutoff properties which has not been known so far in order to solve the above-mentioned problems of the prior art.
The present invention has been accomplished to solve the above-mentioned problems and provides a laminated glass comprising plural glass sheets and an interlayer interposed between the plural glass sheets, wherein the interlayer has heat shielding fine particles with particle diameters of at most 0.2 xcexcm dispersed therein, and at least one of the plural glass sheets is characterized by a UV transmittance as stipulated in ISO-9050 of at most 30%, a visible light transmittance of at least 70% under a standard light source A, a dominant wavelength of from 480 to 570 nm and an excitation purity of at most 6% at the actual thickness.